PRODUCT SPECIFICATION
FAN5035
Pin Assignments
D0
D1
D2
D3
1
24
23
22
21
20
19
18
17
16
15
14
13
COSC
EN_SS
GNDA
2
3
4
5
VREF
A3_INN
D4
IFB_HI
IFB_LO
6
7
8
A3_OUT
A3_INP
FAN5035
VSENSE
VCC
A1_OUT
A1_INN
A1_INP
VIN
9
10
OVP
11
12
PWRGOOD
OUTA
GNDD
Pin Definitions
Pin Number Pin Name Pin Function Description
1–5
D0-4
Voltage Identification Code Inputs. These open collector/TTL compatible inputs
will program the output voltage over the ranges specified in Table 1. Pull-up resistors
are internal to the controller.
6–7
8
IFB_HI
IFB_LO
Current Feedback. These pins are the input for the current feedback control loop.
Layout of these traces is critical to system performance.
VSENSE
VCC
Voltage Sense. Pin 8 is used as the input for Power Good and over-voltage
protection.
9
Analog VCC. Connect to system 5V supply and decouple with a 0.1µF ceramic
capacitor.
10
11
12
13
OVP
Over-Voltage Protection. This pin drives an SCR when the output voltage is too
high.
PWRGOOD Power Good Flag. An open collector output that will be logic LOW if the output
voltage is not within ±10% of the nominal output voltage setpoint.
OUTA
GNDD
VIN
Output. Connect this pin to a driver for an N-channel MOSFET. The trace from this
pin to the driver should be <0.5".
Power Ground. Return pin for high currents flowing in pin 12 (OUTA). Connect to a
low impedance ground.
14
Input Voltage. Under-voltage detector input.
15–17
A1_INP
A1_INN
A1_OUT
Uncommitted Op Amp.
18–20
A3_INP
A3_INN
A3_OUT
Voltage Feedback Op Amp. This op amp is used for voltage feedback from the
output, and for loop compensation.
21
22
VREF
GNDA
Reference Voltage. Decouple with a 0.1µF ceramic capacitor.
Analog Ground. Return path for low power analog circuitry. This pin should be
connected to a low impedance system ground plane to minimize ground loops.
23
24
EN_SS
COSC
Output Enable. A logic LOW on this pin will disable the output. An internal current
source allows for open collector control. This pin also doubles as soft start.
Oscillator Capacitor. Attach a capacitor from pin 24 to ground to set the oscillator
frequency.
2
REV. 1.0.0 10/31/01